A woman with a history of mental illness purposely walked her young
niece and nephew into highway traffic to commit a double-murder
suicide, US prosecutors say.

Marcelle Thibault, 39, was driving
south on the Interstate 495 highway in Lowell, Massachusetts last
week when she turned the car sharply, drove across the median and
northbound lanes, then began driving against traffic in the
breakdown lane, authorities said.

She then stopped and got out of the car, took both children into
her arms and walked onto the highway. She and the children were
struck by two cars and killed.

"We believe that Ms Thibault took her niece and nephew and walked
with them into oncoming traffic on Route 495, tragically resulting
in the deaths of the two young children while taking her own life in
the process," District Attorney Gerry Leone said in a statement.

The young victims were Kaleigh Lambert, five, and Shane Lambert,
four, of Brentwood, New Hampshire.

A statement from the family released by Leone's office pleaded
for prayers and privacy.

"This is a time of terrible tragedy for our families. We love
Marci, Kaleigh, and Shane and we miss them very much," the statement
said. "We ask everyone to join us in prayer for their souls, and to
help us get through this most difficult period of our lives."